The RIM preparation process is a one-step process in which the liquid components are put in a mould, upon which a very rapid polymerization takes place resulting in a plastic article. The pressures applied in that process are much lower than in the much used injection moulding process.
In a RIM preparation process the viscosity of the components put in the moulds is 50 to 10,000 cps, preferably about 1000-3000 cps. In that process the temperature of the components ranges from room temperature for urethanes to about 100.degree.-150.degree. C. for lactams. The mould temperature in a RIM preparation process for lactam is usually between 100.degree. and 220.degree. C. The pressures applied range from 1 to 100 bar, preferably from 1 to 30 bar.
For smaller articles the reaction in the mould must be finished in less than 5 minutes.
The polymerization of a lactam to form nylon has been known for long.
In the U.S. Pat. No. 3,018,273 a process for the anionic polymerization of caprolactam is described using an organomagnesium compound as catalyst and an N-N diacyl compound as activator.
The British Pat. No. 1,067,153 describes a process for preparing nylon block copolymers by polymerizing caprolactam in the presence of various kinds of activators. In the example the use of an isocyanate-terminated polypropylene glycol as activator and of a potassium compound as catalyst is described.
In the U.S. Pat. Nos. 3,862,262, 4,031,164, 4,034,015, 4,223,112, 3,925,325 and 3,965,375, as well as Reissue patent U.S. Pat. No. Re. 30,371, various aspects of the preparation of activators for the polymerization of lactam and of the polymerization of lactam itself are described.
The U.S. Pat. Nos. 4,031,164 and 4,223,112 describe lactam-polyol polyacyl-lactam block copolymers with specific ratios of the various components.
The U.S. Pat. No. 3,862,262 describes lactam-polyol-acyl-polylactam block copolymers.
The U.S. Pat. No. 4,034,015 aims at nylon block copolymers with at least 5% ester end groups.
The other patents mentioned relate to the preparation of ester-amide compounds by condensation of alcohol and acyl-lactam in the presence of various kinds of catalysts.
The European patent application Nos. 67693, 67694 and 67695 laid open to public inspection relate to acyl-halide and acyl-lactam compounds and to a process for preparing nylon block copolymers with these. The acyl-halide and acyl-lactam compounds are described by means of complex formulas.
The U.S. Pat. No. 3,366,608 describes the reaction of an N,N' diacyl-bis caprolactam, such as N,N' sebacoyl-bis-caprolactam, a polyol and a basic catalyst. In that process a nylon block copolymer is obtained.
The German patent application no. 2026672 laid open to public inspection describes the use of polyol-containing polyamides for the production of metallized articles. The polyol-containing polyamides are obtained by anionic polymerization of lactam in the presence of a polyol, a basic lactam catalyst and an activator, such as a diisocyanate.
The U.S. Pat. No. 4,540,516 describes the preparation of N-substituted carbamoyl lactam compounds, while the U.S. Pat. No. 4,540,515 describes the use of such a compound for the preparation of nylon block copolymers.
The European patent application no. 147792 describes the catalytic condensation of imides and alcohols to form esteracyllactam and esteramide-acyl-lactam compounds.
In the U.S. Pat. No. 3,704,280 a process is described for the anionic catalytic polymerization of lactam in the presence of a polyether, in which process the activator used is an isocyanate compound.